1. Field of the Invention
The present invention relates to a magnetic detecting element mainly used for a hard disk device and magnetic sensor, and a method of manufacturing the same. Particularly the present invention relates to a magnetic detecting element having excellent detectivity to a magnetic field, and a method of manufacturing the same.
2. Description of the Related Art
FIG. 21 is a perspective view showing a conventional reproducing magnetic head.
A magnetic detecting element S constituting the magnetic head shown in FIG. 21 comprises a multilayer film comprising a pinned magnetic layer 101, a nonmagnetic material layer 102 and a free magnetic layer 103. Each of the pinned magnetic layer 101 and the free magnetic layer 103 is made of a ferromagnetic material such as NiFe or the like, and the nonmagnetic material layer 102 is made of Cu or the like.
The magnetization direction of the pinned magnetic layer 101 is pinned in a direction. On the other hand, the magnetization direction of the free magnetic layer 103 varies with the external magnetic field applied thereto. As a result, the relative magnetization direction of the free magnetic layer 103 and the pinned magnetic layer 101 varies to change the electric resistance of the magnetic detecting element S. The change in the electric resistance can be converted to a voltage change or current change to detect the external magnetic field. The free magnetic layer 103 is put 5 into a single magnetic domain state in which the magnetization direction is aligned in a direction, for suppressing the occurrence of Barkhausen noise.
In the magnetic head shown in FIG. 21, the magnetic detecting element S is retracted in the height direction (the 10 Y direction shown in the drawing) so as not to be exposed at the surface facing the recording medium.
In FIG. 21, reference numeral 104 denotes a lower shield layer made of a magnetic material such as a NiFe alloy or the like. Also, a lower gap layer made of an insulating material not shown in the drawing is formed on the lower shield layer 104, and a magnetic flux guide layer 105 is formed on the lower gap layer. The magnetic flux guide layer 105 is made of a magnetic material such as a CoFe alloy, a NiFe alloy, a CoFeNi alloy, Co, or the like. The magnetic flux guide layer 105 is magnetically connected to the free magnetic layer 103 of the magnetic detecting element S.
Furthermore, an upper gap layer not shown in the drawing is formed over the magnetic flux guide layer 105 and the magnetic detecting element S, and an upper shield layer 106 made of a magnetic material such as a NiFe alloy or the like is formed on the upper gap layer.
The front end 105a of the magnetic flux guide layer 105 is exposed at the surface facing the recording medium, and thus serves as an induction layer for inducing a change of magnetization in the free magnetic layer 103 of the magnetic detecting element S due to an external magnetic field. The change of magnetization induced in the magnetic flux guide layer 105 due to the external magnetic field is transmitted to the free magnetic layer 103 so that the magnetization direction of the free magnetic layer 103 changes with a change in the external magnetic field.
As shown in FIG. 21, in the magnetic head, the magnetic detecting element S is retracted from the surface facing the recording medium in the height direction to improve heat resistance to thermal asperity, as compared with a magnetic detecting element exposed at the surface facing the recording medium or a magnetic detecting element covered with only a thin protective film. It is also possible to improve the resistance to electrostatic damage caused by electrostatic charge of the surface facing the recording medium.
In the magnetic head shown in FIG. 21, if the magnetic domain of the magnetic flux guide layer 105 is not controlled to give a multidomain structure to the magnetic flux guide layer 105, Barkhausen noise occurs in transmission of a change of magnetization through the magnetic flux guide layer 105.
Therefore, the magnetization of the magnetic flux guide layer 105 as well as the magnetization of the free magnetic layer 103 must be controlled.
Japanese Unexamined Patent Application Publication No. 2001-273613 discloses a magnetoresistive sensor comprising a tunneling magnetoresistive film and a magnetic flux guide layer, wherein the magnetic domains of both a free magnetic layer and the magnetic flux guide layer are controlled.
However, in the magnetoresistive sensor shown in FIGS. 2, 3 and 4 of Japanese Unexamined Patent Application Publication No. 2001-273613, a magnetic flux guide layer 14 must be bent near the tunneling magnetoresistive film in order to connect a magnetic domain control single layer 15 to both a free layer 25 (free magnetic layer) and the magnetic flux guide layer 14, thereby decreasing the flux transmission efficiency of the magnetic flux guide layer 14.
Also, in the magnetoresistive sensor shown in FIG. 5 of Japanese Unexamined Patent Application Publication No. 2001-273613, the magnetic domains of the free magnetic layer 25 formed above the tunneling magnetoresistive film 13 and the magnetic flux guide layer formed below the tunneling magnetoresistive film 13 must be controlled by the magnetic domain control single layer 15. Therefore, the shape of the magnetic domain control layer 15 is complicated to cause a difficulty in appropriate domain control.
Furthermore, in the magnetoresistive sensor shown in FIGS. 6 and 9 of Japanese Unexamined Patent Application Publication No. 2001-273613, the magnetic domain control layer 15 or 45 is formed on the surface of the magnetic flux guide layer 14 or 44 formed below or above the tunneling magnetoresistive film 13 away from the surface facing the tunneling magnetoresistive film 13 to increase the thickness of the magnetoresistive sensor, thereby increasing the gap length.